We surveyed the subsurface structure in eastern Coprates and Capri Chasmata in the equatorial region using high-resolution visible images, digital terrain models, and radar sounding data. We identified subsurface reflectors in four areas of the chasmata. At the stratigraphic exposure on the chasmata walls, the corresponding depth of the reflector is ~60 m. The bulk dielectric constants of the layers above the reflectors are calculated as 3.4-4.0, suggesting a rock-air mixture with ~46.1% porosity, or a rock-air-ice mixture with ~21.2% water-ice fraction. Recent climate models suggest that water-ice is unstable on the surface around the equatorial regions. However, considering the recent high obliquity that occurred ~0.4 Ma and a slow diffusivity of water-ice, the existence of subsurface water-ice deeper than a few meters cannot be ruled out. If water-ice is actually contained in the layer, our results show the maximum volume of putative water-ice in the chasmata is 16.6 km.